Thin film transistor-liquid crystal displays (TFT-LCDs) have been widely used in televisions, cell phones, displays and similar electronic products, and dominated in the flat panel display field due to its advantages, such as steady pictures, realistic images, no irradiation, space saving and less energy consumption.
Because a liquid crystal display panel itself does not give light, a backlight module is required to provide light for displaying. The backlight module mainly includes a light bar, a reflector sheet, a light guide plate, an optical film, an adhesive frame and a rear panel etc.; and since a light-emitting diode (LED) light bar has advantages, such as small volume, low operating voltage, low operating current, even and steady light-emitting, quick response speed, as well as long working life, the backlight module commonly uses an LED light bar; and the LED light bar is formed by arranging a plurality of LED light sources in a certain pattern.
In the production process of a liquid crystal display, a plurality of tests is performed in various production phases, and for example, testing the white balance of the display module is one of the tests. The white balance of a display module is determined by the spectra of the light source in the backlight module to a great extent. Taking the LED light bar as an example, each kind of the LED light bar presents a different spectra, and thus it's necessary to select the required LED light bar. Test is generally performed by using manufactured LED light bars, in which test the spectral characteristics of the LED light bars are mainly detected so as to select the LED light bars of required chrominance as well as brightness degree.
However, the period for manufacturing a LED light bar is relatively long, usually 1˜2 weeks, and it's necessary to select different LED light bars for retest. In this way, it's very easy for the entire researching and manufacturing period of a liquid crystal display to be extended.